Pawl for centrifugal thrower



June 2, 1970 w. WPWOLFE ETAL 3,515,258

PAWL FOR CENTRIFUGAL THROWER 2 Sheets-Sheet 2 Filed March 6, 1968 MQE 9lrrokusys United States Patent U.S. Cl. 198-128 8 Claims ABSTRACT OF THEDISCLOSURE A pawl or paddle used in connection with a centrifugalthrower for throwing material. The pawl is pivoted to the outer end ofan arm on a spider and freely swings. The pawl is made up of two platelike members formed into a V-shape with a narrow web (the plates aresubstantially wider than the web) holding the plates together. The pivotfor the pawl is at the closed end of the V. The pawl thus has asymmetrical configuration when the pawl is rotating. It has a leadingface which slopes forwardl at an angle from a radial plane passingthrough the axis of the spider and the pivot axis of the pawl. Thisgives greater capacity for the same horsepower.

BACKGROUND OF THE INVENTION Field of the invention The present inventionrelates to pawls or paddles used on the impellers of centrifugalthrowers.

Background of the invention The ability to obtain a high output of acentrifugal type material thrower at low horsepower has been sought fora long time. A straight sided swinging paddle or pawl used withimpellers has not given the maximum output, and various differentdesigns have been advanced. Included are scooping type impellers whichtheoretically are supposed to give additional capacity by providing ascoop type action as they rotate and engage the material to be thrown.However, these pawls or paddles are expensive to manufacture and alsorequire a substantial amount of horsepower for the amount of capacity.The problem has been to keep the cost of manufacture down and stillincrease output without increasing horsepower requirements.

SUMMARY OF THE INVENTION The present invention relates to a pawl orpaddle for the impeller of a centrifugal thrower having at least oneforwardly inclined face which will engage material as the impellerrotates and throw the material outwardly under centrifugal force. Theweight of the material tends to move the pawl rearwardly about its pivotand the centrifugal force on the pawl tends to hold it in its normalradial position. The leading face then assumes a natural angle wheremaximum throwing capacity is achieved. As shown, when a V-shaped pawl isused the pawl is made using two blades shaped in a V and held togetherwith a narrow web at right angles to the planes of the blades. Therearward slanting blade of the pawl has a leading face on either side ofthe web and this leading face will tend to create an outward rush of airimmediately following the material being thrown outwardly and tends togive an extra boost to the material.

The symmetrical design of the pawl permits the pawl to be reversed indirection as wear occurs to increase the effective life of a single pawlthereby reducing operating and maintenance costs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view showinga centrifugal thrower of the type using a pawl made according to thepresent invention;

FIG. 2 is a sectional view taken on line 22 of FIG. 1;

FIG. 3 is a sectional view taken on line 3-3 in FIG. 2; and

FIG. 4 is a sectional view taken on line 4-4 in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, first, acentrifugal thrower 10' is shown to illustrate the environment in whichthe pawl operates. The thrower is moving material 11, such as choppedcorn or grass or other material. The thrower assembly includes a frame13 mounting a rotor drive motor 14 which obtains electric power throughsuitable connections and which is used to drive the rotor of thethrower. An auger trough 15 which, in turn, rotatably mounts an auger16, extends laterally from a thrower housing 17. The terminology used inthis specification will be thrower for the assembly but it can also betermed a blower of the centrifugal type. However, the action here ismore of a scooping and throwing action rather than blowing. A separatemotor 18 is mounted to the outer end of the trough 15 and a driveassembly, such as a chain and sprocket is attached from the output shaftof the motor to the shaft for auger 16. The motor 18 is also poweredfrom an electrical source. Material to be lifted by the thrower isplaced in the auger housing and conveyed by the anger (with motor 18running) toward housing 17. When the material reaches the housing 17 itis engaged by the thrower and the material will be thrown up through aguide chute 22 and out of the machine into the desired location. Theguide chute 22 has a gooseneck portion at its upper end which can berotated to any desired position.

The motor 14 drives an exial shaft 24 mounted in the housing 17 withsuitable bearings 25 mounted on the side walls of the housing. A rotorassembly 26 is mounted on the shaft 24 and has a hub which is pinned tothe shaft so that it will turn with the shaft. The rotor assemblyincludes a spider 27 which, as shown, has 3 arms. On the outer end ofthe arms of the spider there are hubs 28.

A pair of swinging pawls or paddles 30 are mounted onto the oppositesides of each of the hubs 28 with a pin 31 that is held in place in aconvenient manner such as with the use of a spring pin. These pawls arefree to swing around the axis of the pins 31, and are placed in a sideby side position. As can be seen, the outer ends of the pawls provide asmall clearance with the periphery of the housing 17 and there is asmall bit of side clearance along the pawls.

The pawls themselves each have a hub 32 that is bored to receive thepins 31. A pair of blade members 33 and 34 (leading and trailing) areintegral with the hubs 32 and are joined together with a web 35. The web35 has been put in at right angles to the planes of the blade members 33and 34 and is relatively narrow and positioned in the center of theseblade members. The outer ends of the blade members are cut as shown at36 on a plane at right angles to a radial plane passing through the axesof spider 26 and pin 31. There is no obstruction for movement ofmaterial along the sides of the web 32 outwardly as shown by the arrows37 in FIG. -4.

The rotor is rotating as indicated by the arrow 40, and material orsilage 11 moved into the housing 17 by the auger 15 will be engaged bythe leading face 33L of the leading blade 33 of each of the paddles asthey rotate. A quantity of material will be carried around by thepaddle. The plane of the face 33L will remain advanced from a radialplane passing through the axes of the pin 31 and the shaft 24. Thisgives a leading face for carrying the material, and centrifugal force onthe material will tend to throw it outwardly through the dischargeopening 41 of the housing 17. The leading face of each pawl tends tobuild up the velocity pressure of the material as it discharges. In anordinary single plane paddle there is a vacuum created at the trailingface of the paddle. However, the trailing blade 34 also has air flowingoutwardly along its leading face 34L (on either side of the web) andthis tends to overcome any vacuum effect. This additional air coming outalong the paddle 34L will give an added boost to the material thrown bythe leading blade 33. This design gives an additional capacity toblowers or throwers without increasing the horsepower requirement. Ifnecessary, the housing can be provided with suitable openings along itssides for letting make-up air flow in.

As shown, the blades incline from a bisecting radial line on the paddleapproximately in either direction, or in other words, the two blades 33and 34 form an included angle of approximately 30. This inclination issufiicient to make sure that there is a forward incline to the leadingface of the leading paddle with respect to a radial line even when it isloaded. Only one blade with a leading face also would be beneficial, butit would have to be balanced with respect to its attachment axis. Whenthe spider is rotating the leading face should be at a leading anglewith respect to the radial plane passing through the axis of the spiderand the pivot axis of the pawl.

The use of the two blades with only a narrow joined web (in radialdirection) and an open end between the blades permits the material toflow off the leading face of the leading blade, and air to flow off theleading face of the trailing blade. There are no obstructions for thisair flow at the outer end of the web. The paddles or pawls arefree-swinging, and will assume their natural position as they rotate.

What is claimed is:

1. In a device for moving material comprising a housing, a rotor mountedfor rotation about a rotor axis inside said housing, said housing has adischarge opening for discharging material, the improvement comprising apawl pivotally mounted adjacent to the outer periphery of said rotor forfree swinging movement about a pawl axis, said pawl comprising a firstblade member having a planar rotationally leading surface extending onone side of said pawl axis only and extending substantially the fullwidth of said pawl in the outer end portions thereof and beingsubstantially parallel to said pawl axis, and means fixed to said blademember comprising counterweight means which causes the blade member tomove on the opposite side of said pawl axis from the rotor axis andholds the planar leading surface of said blade member inclined at arotationally leading angle with respect to a radial plane passingthrough the rotor axis and the pawl axis under centrifugal force whenthe rotor is rotating, said blade member being substantiallyunobstructed along the side edges thereof on both the leading andtrailing surfaces thereof.

2. The combination as specified in claim 1 wherein said pawl comprisestwo blade like members formed into a 4 general V-shape, with the closedend of the V adjacent the pawl axis, and means holding said blade likemembers in position with respect to the axis, so that said pawl issymmetrical about a bisecting line passing through the pivotal axis ofsaid pawl.

3. The combination as specified in claim 2 wherein said means joiningsaid blade like members together comprises a web, said web being afurther plate like member of very narrow cross-section dimensionpositioned at substantially right angles to the planes of said bladelike members.

4. The combination as specified in claim 3 wherein the space betweensaid blade like members is substantially unobstructed at the outer endof said pawl.

5. The combination as specified in claim 3 wherein there are two pawlmounted side by side about a common axis on said mounting member, thetwo pawls together being leading surfaces extending substantially acrossthe width of the housing.

6. The combination specified in claim 3 wherein the blade like membershave an included angle of substantially 30.

7. A pawl for a solid material thrower having a rotor rotating about arotor axis, including a hub having means for pivotally mounting saidpawl for free swinging movement about a pawl axis at one end of saidpawl to the periphery of said rotor, a pair of blade members fixed tosaid hub, said blade members being positioned to form a V-shape andbeing fixed to said hub and spaced apart throughout their length, saidblade members having substantialy planar outwardly facing surfacesparallel to said pawl axis and having a width at the outer end portionsthereof in direction along said axis substantially equal to the greatestwidth of the pawl in said direction and each being substantially thinnerthan said width, said blade members diverging from said hub atsubstantially equal angles with respect to a bisecting plane passingthrough said pawl axis, said hub having axial length substantially lessthan the width of said blade members at the outer portions thereof, saidblade members tapering from their maximum width to the width of said hubadjacent said hub, and a web member substantially narrower in directionalong said pawl axis than said blade members joining said blade memberstogether, there being no other connecting members between said blademembers.

8. The combination as specified in claim 7 wherein each blade member hasan inner face surface forming the inner portions of the V-shapeextending from opposite sides of said web to the edges of said blademembers, said inner surfaces being substantially parallel to therespective outwardly facing surfaces of said blade member.

References Cited UNITED STATES PATENTS 2,587,154 2/1952 Hartz 103-972,958,412 11/1960 Buschbom 198-128 FOREIGN PATENTS 88,019 8/1896Germany.

RICHARD E. AEGERTER, Primary Examiner U.S. Cl. X.R. 239672

